Epigenetic modulation elicits an NK cell-mediated immune response in urothelial carcinoma

Urothelial carcinoma of the bladder, the second most prevalent cancer within the urothelial system, often evades immune recognition by natural killer (NK) cells, but studies have shown that cyproheptadine (CPH), an anti-histamine drug, exhibits anticancer effects in this carcinoma. Co-culturing CPH-treated cells with NKG2D-expressing NK92 cells resulted in enhanced NK-mediated lysis of UC cells, with RNA-seq analysis revealing increased expression of the NKG2D ligand ULBP2 in CPH-treated cells. We hypothesize that cyproheptadine as a epigenetic modifier enhances NK-mediated cytotoxicity by restoring NKG2D ligands and CCL3 and as a control we used entinostat a known FDA approved HDAC1/3 inhibitor. Targeting NK cells offers a promising strategy against urothelial carcinoma. Further analysis showed epigenetic regulation of ULBP2 expression with increased H3K27Ac active mark enrichment in CPH-treated cells. Overexpression of ULBP2 led to increased NK-mediated lysis, while knockdown reduced it in CPH-treated urothelial carcinoma cells. Additionally, CPH treatment enhanced the anti-tumor effect in a mouse model, likely due to increased NK and NKT cell infiltration. In summary, CPH triggers an innate immune response against urothelial carcinoma by promoting NK cell-mediated cytotoxicity through ULBP2 and CCL3 restoration.